Two blocks `A` and `B` , each of mass `10 kg` , are connected by a light string passing over a smooth pulley as shown in the figure. Block `A` will remain at rest if the friction on it is

Options

A. `50 N` up the plane
B. `50 N` down the plane
C. `100 N` up the plane
D. `100 N` down the plane

Answer

B

Explanation

`100 = 100 sin 30^(@) + f`
`f = 50 N`